Pharmacologic activity and pharmacokinetics of metabolites of regorafenib in preclinical models

Regorafenib Enhances the Efficacy of Photodynamic Therapy in Hepatocellular carcinoma through MAPK Signaling Pathway Suppression

Photodynamic therapy (PDT) is a promising and innovative approach for treating tumors. The synergistic effect of PDT and chemotherapy can enhance the anti-tumor efficacy by leveraging their complementing benefits. In this study, we created lipid vesicles to deliver a photosensitizer (chlorin e6, Ce6) and Regorafenib into tumors for the purpose of examining the effectiveness and mechanism of Lipo-Ce6@Rego-PDT (LCR-P) on Hepatocellular carcinoma (HCC) both in vitro and in vivo. We found that the cytotoxicity on HCC caused by LCR-P was significantly stronger than that caused by Lipo-Ce6-PDT (LC-P). Cellular ROS production in the LCR-P group was approximately higher than that in the LC-P group, and Regorafenib significantly inhibited the phosphorylation of JNK, ERK, and P38 of Lipo-Ce6-PDT group in vitro and in vivo. Furthermore, Regorafenib significantly downregulated the expression of Bcl-2 and upregulated the expression of Bax and cleaved caspase-3 of LC-P group in vitro and in vivo. Compared with LC-P, LCR-P significantly increased cell apoptosis rate. The body weight and HE staining of normal organs primarily indicated the safety of this combined strategy. These results indicate that the combination of Regorafenib and Lipo-Ce6 can significantly enhance the anti-tumor efficiency of PDT for HCC and exhibits good biosafety.

Current status of drugs targeting PDGF/PDGFR

As an important proangiogenic factor, platelet-derived growth factor (PDGF) and its receptor PDGFR are highly expressed in a variety of tumors, fibrosis, cardiovascular and neurodegenerative diseases. Targeting the PDGF/PDGFR pathway is therefore a promising therapeutic strategy. At present, a variety of PDGF/PDGFR targeted drugs with potential therapeutic effects have been developed, mainly including PDGF agonists, inhibitors targeting PDGFR and proteolysis targeting chimera (PROTACs). This review clarifies the structure, biological function and disease correlation of PDGF and PDGFR, and it discusses the current status of PDGFR-targeted drugs, so as to provide a reference for subsequent research.

Pharmacokinetic interaction between regorafenib and atorvastatin in rats

BACKGROUND

Regorafenib is used in the treatment of colorectal cancer and hepatocellular carcinoma. Due to the co-morbidity of hyperlipidemia in these conditions, statins, including atorvastatin, are used as potential adjuvant therapy agents. Both regorafenib and atorvastatin are metabolized by CYP3A4. In addition, atorvastatin is a P-gp and BCRP substrate, whereas regorafenib and its active metabolites M-2 and M-5 are inhibitors of these transporters. Hence, the concomitant use of both drugs may increase the risk of a clinically significant drug-drug interaction. Therefore, the present study aimed to assess the pharmacokinetic interactions of atorvastatin and regorafenib and their active metabolites.

METHODS

Male Wistar rats were assigned to three groups (eight animals in each) and were orally administered: regorafenib and atorvastatin (IREG+ATO), a carrier with regorafenib (IIREG), and atorvastatin with a carrier (IIIATO). Blood samples were collected for 72 h. UPLC-MS/MS was the method of measurement of regorafenib and atorvastatin concentrations. The pharmacokinetic parameters were calculated with a non-compartmental model.

RESULTS

A single administration of atorvastatin increased the exposure to regorafenib and its active metabolites. In the IREG+ATO group, the Cmax, AUC0-t, and AUC0-∞ of regorafenib increased 2.7, 3.2, and 3.2-fold, respectively. Atorvastatin also significantly increased the Cmax, AUC0-t, and AUC0-∞ of both regorafenib metabolites. Regorafenib, in turn, decreased the AUC0-t and AUC0-∞ of 2-OH atorvastatin by 86.9% and 67.3%, and the same parameters of 4-OH atorvastatin by 45.0% and 46.8%, respectively.

CONCLUSIONS

This animal model study showed a significant pharmacokinetic interaction between regorafenib and atorvastatin. While this interaction may be clinically significant, this needs to be confirmed in clinical trials involving cancer patients.

Regorafenib and glioblastoma: a literature review of preclinical studies, molecular mechanisms and clinical effectiveness

Glioblastoma IDH wild type (GBM) is a very aggressive brain tumour, characterised by an infiltrative growth pattern and by a prominent neoangiogenesis. Its prognosis is unfortunately dismal, and the median overall survival of GBM patients is short (15 months). Clinical management is based on bulk tumour removal and standard chemoradiation with the alkylating drug temozolomide, but the tumour invariably recurs leading to patient's death. Clinical options for GBM patients remained unaltered for almost two decades until the encouraging results obtained by the phase II REGOMA trial allowed the introduction of the multikinase inhibitor regorafenib as a preferred regimen in relapsed GBM treatment by the National Comprehensive Cancer Network (NCCN) 2020 Guideline. Regorafenib, a sorafenib derivative, targets kinases associated with angiogenesis (VEGFR 1-3), as well as oncogenesis (c-KIT, RET, FGFR) and stromal kinases (FGFR, PDGFR-b). It was already approved for metastatic colorectal cancers and hepatocellular carcinomas. The aim of the present review is to focus on both the molecular and clinical knowledge collected in these first three years of regorafenib use in GBM.

Efficacy of tyrosine kinase inhibitors in patients with advanced or metastatic sarcomas after prior chemotherapy: A meta-analysis

BACKGROUND

Sarcoma is a heterogeneous malignancy arising from interstitial tissue. Anthracycline-based therapy is the first-line treatment recommended by guidelines for patients with locally advanced or metastatic unresectable sarcoma. Recently, targeted therapies, in particular tyrosine kinase inhibitors (TKIs), have made significant progress in the treatment of sarcoma, and their efficacy has been investigated in randomized controlled trials. The aim of this meta-analysis is to evaluate the efficacy of TKIs in patients with advanced or metastatic sarcoma who have previously received chemotherapy.

METHODS

We completed a meta-analysis after conducting literature searches in PubMed, Embase, and Cochrane. The single-drug, placebo-controlled, randomized controlled clinical trials of TKIs in patients with advanced or progressive sarcoma who have previously received chemotherapy are available for inclusion in the study. The observation results were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS). The subgroup analysis was performed according to histological subtypes of sarcoma.

RESULTS

This study included 6 studies, including 1033 patients. The ORR (OR: 7.99, 95% CI: 3.62-19.61, P < .00001), DCR (OR: 2.54, 95% CI: 1.27-5.08, P = .009), PFS (HR: 0.46, 95% CI: 0.34-0.62, P < .00001), and OS (HR: 0.80, 95% CI: 0.67-0.96, P = .02) of patients treated with TKIs were better than those in the placebo group.

CONCLUSIONS

In patients with advanced sarcoma, TKIs have been shown to have advantages in terms of ORR, DCR and PFS and OS. Multi-targeted TKIs may be considered as one of the second-line treatment options for sarcoma patients who have received prior chemotherapy.

Effect of Intraperitoneal Chemotherapy with Regorafenib on IL-6 and TNF-α Levels and Peritoneal Cytology: Experimental Study in Rats with Colorectal Peritoneal Carcinomatosis

Cytoreductive surgery (CRS), combined with hyperthermic intraperitoneal chemotherapy, has significantly improved survival outcomes in patients with peritoneal carcinomatosis from colorectal cancer (CRC). Regorafenib is an oral agent administered in patients with refractory metastatic CRC. Our aim was to investigate the outcomes of intraperitoneal administration of regorafenib for intraperitoneal chemotherapy (IPEC) or/and CRS in a rat model of colorectal peritoneal metastases regarding immunology and peritoneal cytology. A total of 24 rats were included. Twenty-eight days after carcinogenesis induction, rats were randomized into following groups: group A: control group; group B: CRS only; group C: IPEC only; and group D: CRS + IPEC. On day 56 after carcinogenesis, euthanasia and laparotomy were performed. Serum levels of interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) as well as peritoneal cytology were investigated. Groups B and D had statistically significant lower mean levels of IL-6 and TNF-α compared to groups A and C, but there was no significant difference between them. Both B and D groups presented a statistically significant difference regarding the rate of negative peritoneal cytology, when compared to the control group, but not to group C. In conclusion, regorafenib-based IPEC, combined with CRS, may constitute a promising tool against peritoneal carcinomatosis by altering the tumor microenvironment.

Anti-angiogenic therapy using the multi-tyrosine kinase inhibitor Regorafenib enhances tumor progression in a transgenic mouse model of ß-cell carcinogenesis

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) represent a distinct hypervascularized tumor entity, often diagnosed at metastatic stage. Therapeutic efficacy of anti-angiogenic multi-kinase inhibitors is frequently limited by primary or acquired resistance in vivo. This study aimed to characterize the molecular mode of action as well as resistance mechanisms to the anti-angiogenic multi-tyrosine kinase inhibitor (TKI) Regorafenib in vitro and in vivo.

METHODS

In vitro, human and murine pancreatic neuroendocrine cell lines were comparatively treated with Regorafenib and other TKIs clinically used in PNETs. Effects on cell viability and proliferation were analyzed. In vivo, transgenic RIP1Tag2 mice were treated with Regorafenib at two different time periods during carcinogenesis and its impact on angiogenesis and tumor progression was evaluated.

RESULTS

Compared to the established TKI therapies with Sunitinib and Everolimus, Regorafenib showed the strongest effects on cell viability and proliferation in vitro, but was unable to induce apoptosis. Unexpectedly and in contrast to these in vitro findings, Regorafenib enhanced proliferation during early tumor development in RIP1Tag2 mice and had no significant effect in late tumor progression. In addition, invasiveness was increased at both time points. Mechanistically, we could identify an upregulation of the pro-survival protein Bcl-2, the induction of the COX2-PGE2-pathway as well as the infiltration of CSF1R positive immune cells into the tumors as potential resistance mechanisms following Regorafenib treatment.

DISCUSSION

Our data identify important tumor cell-autonomous and stroma-dependent mechanisms of resistance to antiangiogenic therapies.

Evaluating the Pharmacokinetics and Pharmacodynamics of Chemotherapeutics within a Spatial SILAC-Labeled Spheroid Model System

Tumors have considerable cellular heterogeneity that is impossible to explore with simple cell cultures. Spheroid cultures contain pathophysiological and chemical gradients similar to in vivo tumors and show complex responses to therapeutics, similar to a tumor. Using pulsed isotopic labels, we demonstrate the pronounced differential response of the proteome to the drug Regorafenib, a multikinase inhibitor, in HCT 116 spheroids. Regorafenib treatment of outer spheroids inhibits proteins involved in critical pathways such as mTOR signaling, extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling, and colorectal cancer metastasis signaling, resulting in decreased proliferation and cellular apoptosis. By contrast, analysis of the treated core cells shows upregulation of MAPK1 and KRAS, possibly implicating drug resistance within these late apoptotic cells. Thus, pulsed isotopic labeling enables evaluation of the distinct proteomic responses for cells residing in the different chemical microenvironments of the spheroid. This platform promises great utility in assisting researchers' predictions of pharmacodynamic therapeutic responses within complex tumors.

Pharmacokinetic considerations for angiogenesis inhibitors used to treat hepatocellular carcinoma: an overview

INTRODUCTION

Hepatocellular carcinoma (HCC) is the fifth malignancy in terms of frequency and the fourth malignancy in terms of cancer-related death worldwide. Systemic therapy of advanced HCC has probably gone through the greatest wave of change in the last decade, with the introduction of several anti-angiogenic drugs and immune checkpoint inhibitors, able to significantly improve patients' prognosis.

AREAS COVERED

In this review, we summarize the pharmacokinetic characteristic of the antiangiogenic drugs currently approved for the treatment of HCC, from oral tyrosine kinase inhibitors (sorafenib, lenvatinib, regorafenib and cabozantinib) to monoclonal antibodies (bevacizumab and ramucirumab), focusing on the main aspects that differ among compounds from the same class, on factors that can exert an influence on pharmacokinetic parameters and the main issues that could limit their clinical use.

EXPERT OPINION

Anti-angiogenic drugs have different profiles in terms of bioavailability, metabolism, elimination and interindividual variability in their pharmacokinetics and effectiveness. More studies should be developed to address the intrinsic and extrinsic factors influencing pharmacokinetics parameters to improve the individual therapeutic response and, furthermore, to evaluate the benefit and the harm of systemic therapy for advanced HCC in selected patients with liver impairment.

Effects of regorafenib on the mononuclear/phagocyte system and how these contribute to the inhibition of colorectal tumors in mice

BACKGROUND

Regorafenib was previously shown to reduce tumor-associated macrophages and potently inhibit colony-stimulating factor 1 receptor (CSF1R), also known as CD115, in biochemical assays. The CSF1R signaling pathway is essential in the biology of the mononuclear/phagocyte system, which can promote the development of cancer.

METHODS

A deeper investigation of regorafenib's effects on CSF1R signaling was performed using preclinical in vitro and in vivo studies with syngeneic CT26 and MC38 mouse models of colorectal cancer. Peripheral blood and tumor tissue were analyzed mechanistically by flow cytometry using antibodies against CD115/CSF1R and F4/80 and by ELISA for chemokine (C-C motif) ligand 2 (CCL2) levels. These read-outs were correlated with drug levels for the detection of pharmacokinetic/pharmacodynamic relationships.

RESULTS

Potent inhibition of CSF1R by regorafenib and its metabolites M-2, M-4, and M-5 was confirmed in vitro in RAW264.7 macrophages. The dose-dependent growth inhibition of subcutaneous CT26 tumors by regorafenib was associated with a significant reduction in both the number of CD115^hi monocytes in peripheral blood and the number of selective subpopulations of intratumoral F4/80^hi tumor-associated macrophages. CCL2 levels were not affected by regorafenib in blood but increased in tumor tissue, which may contribute to drug resistance and prevent complete tumor remission. An inverse relationship between regorafenib concentration and the number of CD115^hi monocytes and CCL2 levels was observed in peripheral blood, supporting the mechanistic involvement of regorafenib.

CONCLUSIONS

These findings may be clinically useful in optimizing drug dosing using blood-based pharmacodynamic markers and in identifying resistance mechanisms and ways to overcome them by appropriate drug combinations.

Adeno-associated virus-mediated knockdown demonstrates the major role of hepatic Bcrp in the overall disposition of the active metabolite of the tyrosine kinase inhibitor regorafenib in mice

Breast cancer resistance protein (BCRP) is expressed on hepatic bile canalicular membranes; however, its impact on substrate drug disposition is limited. This study proposes an in vivo knockdown approach using adeno-associated virus encoding short hairpin RNA (shRNA) targeting the bcrp gene (AAV-shBcrp) to clarify the substrate, the overall disposition of which is largely governed by hepatic Bcrp. The disposition of the tyrosine kinase inhibitor, regorafenib, was first examined in bcrp gene knockout (Bcrp^-/-) and wild-type (WT) mice, as it was sequentially converted to active metabolites M - 2 and M - 5, which are BCRP substrates. After oral administration of regorafenib, plasma and liver concentrations of M - 5, but not regorafenib, were higher in Bcrp^-/- than WT mice. To directly examine the role of hepatic Bcrp in M - 5 disposition, M - 5 was intravenously injected into mice three weeks after the intravenous injection of AAV-shBcrp, when mRNA of Bcrp in the liver (but not the small intestine) was downregulated. AAV-shBcrp-treated mice showed higher M - 5 concentration in plasma and liver, but lower biliary excretion than the control mice, indicating the fundamental role of hepatic Bcrp in M - 5 disposition. This is the first application of AAV-knockdown strategy to clarify the pharmacokinetic role of xenobiotic efflux transporters in the liver.

Efficacy and Safety of TACE Combined with Regorafenib Plus PD-1 Inhibitor in the Treatment of Hepatocellular Carcinoma After Sorafenib Resistance

Purpose

To evaluate the efficacy and safety of TACE combined with regorafenib plus PD-1 inhibitor as a second-line therapy for hepatocellular carcinoma after sorafenib resistance.

Materials and Methods

The clinical data of 76 patients with hepatocellular carcinoma who were drug-resistant to sorafenib from September 2018 to May 2022 in the tumor intervention department were collected. Among them, 35 patients used TACE combined with regorafenib plus PD-1 inhibitor (TACE-R-P) as second-line treatment, and the remaining 41 patients used TACE combined with regorafenib (TACE-R) as second-line treatment. The mRECIST (modified Response Evaluation Criteria in Solid Tumors) standard was used to evaluate the therapeutic effect. The progression-free survival (PFS) and overall survival (OS) of the two groups were compared. Blood samples were collected before and after treatment to detect the changes in biochemical indicators, and the adverse events (AEs) related to treatment were recorded.

Results

A total of 76 patients were included in the study, including 35 patients receiving TACE-R-P treatment and 41 patients receiving TACE-R treatment. Patients in the TACE-R-P group had longer median OS (19.7months vs 15.2months, HR:0.7716, 95% CI:0.4767-1.2490, P=0.03), longer median PFS (6.3months vs 3.8months, HR:0.6032, 95% CI:0.3727-0.9763, P=0.0029), higher objective response rate (37.14% vs 19.51%, P=0.001) and higher disease control rate (71.43% vs 48.78%, P=0.001) than those in the TACE-R group. Multivariate analysis showed that Child-Pugh grade (B/A; HR=1.283, 95% CI: 0.623-1.707, P=0.014), PVTT (Yes/No, HR=1.455, 95% CI: 0.977-2.038, P=0.018), extrahepatic metastasis (Yes/No, HR=1.766, 95% CI: 1.135-2.302, P=0.022) and treatment option (TACE-R/TACE-R-P, HR=1.930, 95% CI: 1.461-2.850, P=0.017) were independent prognostic factors for OS. There was no significant difference in the incidence and severity of AEs between the two groups.

Conclusion

TACE-R-P treatment can be more effective than TACE-R treatment for HCC after sorafenib resistance and can be given priority as a second-line treatment for HCC.

Regorafenib induces Bim-mediated intrinsic apoptosis by blocking AKT-mediated FOXO3a nuclear export

Regorafenib (REGO) is a synthetic oral multi-kinase inhibitor with potent antitumor activity. In this study, we investigate the molecular mechanisms by which REGO induces apoptosis. REGO induced cytotoxicity, inhibited the proliferation and migration ability of cells, and induced nuclear condensation, and reactive oxygen species (ROS)-dependent apoptosis in cancer cells. REGO downregulated PI3K and p-AKT level, and prevented FOXO3a nuclear export. Most importantly, AKT agonist (SC79) not only inhibited REGO-induced FOXO3a nuclear localization and apoptosis but also restored the proliferation and migration ability of cancer cells, further demonstrating that REGO prevented FOXO3a nuclear export by deactivating PI3K/AKT. REGO treatment promotes Bim expression via the FOXO3a nuclear localization pathway following PI3K/AKT inactivation. REGO induced Bim upregulation and translocation into mitochondria as well as Bim-mediated Bax translocation into mitochondria. Fluorescence resonance energy transfer (FRET) analysis showed that REGO enhanced the binding of Bim to Bak/Bax. Knockdown of Bim, Bak and Bax respectively almost completely inhibited REGO-induced apoptosis, demonstrating the key role of Bim by directly activating Bax/Bak. Knockdown of Bax but not Bak inhibited REGO-induced Drp1 oligomerization in mitochondria. In conclusion, our data demonstrate that REGO promotes apoptosis via the PI3K/AKT/FOXO3a/Bim-mediated intrinsic pathway.

Regorafenib Induces Senescence and Epithelial-Mesenchymal Transition in Colorectal Cancer to Promote Drug Resistance

Potential intrinsic resistance mechanisms to regorafenib were explored after short exposure (3 days) on five CRC cell lines (HCT-116, SW1116, LS-1034, SW480, Caco-2). The observation of senescence-like features led to the investigation of a drug-initiated phenotype switch. Following long-term exposure (12 months) of HCT-116 and SW480 cell lines to regorafenib, we developed resistant models to explore acquired resistance. SW480 cells demonstrated senescent-like properties, including a cell arrest in the late G2/prophase cell cycle stage and a statistically significant decrease in the expression of G1 Cyclin-Dependent Kinase inhibitors and key cell cycle regulators. A specific senescence-associated secretome was also observed. In contrast, HCT-116 treated cells presented early senescent features and developed acquired resistance triggering EMT and a more aggressive phenotype over time. The gained migration and invasion ability by long-exposed cells was associated with the increased expression level of key cellular and extracellular EMT-related factors. The PI3K/AKT pathway was a significant player in the acquired resistance of HCT-116 cells, possibly related to a PI3KCA mutation in this cell line. Our findings provide new insights into the phenotypic plasticity of CRC cells able, under treatment pressure, to acquire a stable TIS or to use an early senescence state to undergo EMT.

Efficacy and Safety of Regorafenib with or without PD-1 Inhibitors as Second-Line Therapy for Advanced Hepatocellular Carcinoma in Real-World Clinical Practice

Background

Regorafenib is the first oral targeted drug as a second-line agent in patients with advanced hepatocellular carcinoma (HCC) who progressed on sorafenib treatment. Recently, several studies demonstrated that the combination of regorafenib and PD-1 inhibitors showed a synergistic effect. Our study aimed to evaluate the efficacy of regorafenib with PD-1 inhibitors (RP) and regorafenib alone (R) as second-line treatment for advanced HCC.

Methods

From October 2018 to January 2022, our retrospective study evaluated advanced HCC patients who received regorafenib with PD-1 inhibitors or regorafenib alone as a second-line treatment at the Second Affiliated Hospital of Nanchang University, China. The efficacy and safety were compared between RP and R groups.

Results

In total, 78 patients were enrolled in our study and were separated into two groups – RP group (48) and R group (30) – according to the criteria. The ORR of RP group and R group was 18.8% and 10%, respectively, and the DCR was 66.7% and 43.3%, respectively. The RP group had a longer mPFS (5.9 months vs 3.0 months, P<0.001) and mOS (12.9 months vs 10.3 months, P=0.010) than the R group. Regorafenib monotherapy is an independent prognostic factor for OS and PFS. In OS, subgroup analysis showed that patients with AFP ≥ 400ng/mL, BCLC C stage and extrahepatic metastasis may benefit from RP, while in PFS, subgroup analysis showed that patients with BCLC C stage, AFP ≥ 400ng/mL, extrahepatic metastasis, ALBI ≥-2.60 and first-line treatment of sorafenib may benefit from RP. The incidence of grade 3/4 adverse reaction in the two groups was 22.9% and 23.3%, respectively, with no significant statistically difference (P=0.966).

Conclusion

In the second-line therapy of advanced HCC, compared to regorafenib alone, the combination of regorafenib and PD-1 inhibitors showed promising efficacy and tolerable drug toxicity.

Chidamide plus Tyrosine Kinase Inhibitor Remodel the Tumor Immune Microenvironment and Reduce Tumor Progression When Combined with Immune Checkpoint Inhibitor in Naïve and Anti-PD-1 Resistant CT26-Bearing Mice

Combined inhibition of vascular endothelial growth factor receptor (VEGFR) and the programmed cell death protein 1 (PD-1) pathways has shown efficacy in multiple cancers; however, the clinical outcomes show limited benefits and the unmet clinical needs still remain and require improvement in efficacy. Using murine colon carcinoma (CT26) allograft models, we examined the efficacy and elucidated novel tumor microenvironment (TME) remodeling mechanisms underlying the combination of chidamide (a benzamide-based class l histone deacetylase inhibitor; brand name in Taiwan, Kepida®) with VEGF receptor tyrosine kinase inhibitor (TKIs; cabozantinib/regorafenib, etc.) and immune checkpoint inhibitors (ICIs; anti-PD-1/anti-PD-L1/anti-CTLA-4 antibodies). The TME was assessed using flow cytometry and RNA-sequencing to determine the novel mechanisms and their correlation with therapeutic effects in mice with significant treatment response. Compared with ICI alone or cabozantinib/regorafenib + ICI, combination of chidamide + cabozantinib/regorafenib + ICI increased the tumor response and survival benefits. In particular, treatment of CT26-bearing mice with chidamide + regorafenib + anti-PD-1 antibody showed a better objective response rate (ORR) and overall survival (OS). Similar results were observed in anti-PD-1 treatment-resistant mice. After treatment with this optimal combination, in the TME, RNA-sequencing revealed that downregulated mRNAs were correlated with leukocyte migration, cell chemotaxis, and macrophage gene sets, and flow cytometry analysis showed that the cell numbers of myeloid-derived polymorphonuclear suppressor cells and tumor-associated macrophages were decreased. Accordingly, chidamide + regorafenib + anti-PD-1 antibody combination therapy could trigger a novel TME remodeling mechanism by attenuating immunosuppressive cells, and restoring T-cell activation to enhance ORR and OS. Our studies also showed that the addition of Chidamide to the regorafenib + anti-PD-1 Ab combination could induce a durable tumor-specific response by attenuating immune suppression in the TME. In addition, this result suggests that TME remodeling, mediated by epigenetic immunomodulator combined with TKI and ICI, would be more advantageous for achieving a high objective response rate, when compared to TKI plus ICI or ICI alone, and maintaining long-lasting antitumor activity.

Impact of trough concentrations of regorafenib and its major metabolites M-2 and M-5 on overall survival of chemorefractory metastatic colorectal cancer patients: Results from a multicentre GERCOR TEXCAN phase II study

PURPOSE

This prospective pharmacokinetic (PK) ancillary study of the TEXCAN phase II GERCOR trial of patients with chemorefractory metastatic colorectal cancer and treated with regorafenib (REGO) investigated correlations between overall survival (OS) and concentrations (C) of REGO and its active metabolites, M-2 and M-5.

METHODS

55 patients received REGO 160 mg/day for 21 days of a 28-day cycle (NCT02699073). REGO, M-2, M-5 were measured by liquid chromatography-mass spectrometry assay on day 15 of cycle 1 (C1) and 2 (C2). We studied the association between OS and Cmin of REGO, M-2 and M-5 at C1 and their accumulations between C1 and C2.

RESULTS

Medians of C2/C1 M-2 and M-5 ratios were 0.82 (interquartile range 0.50-1.78) and 0.75 (interquartile range 0.41-1.93), respectively. Patients with C2/C1 M-2 ratio ≥ median had improved survival compared to those < median (12.6 versus 4.0 months, P = 0.023), corresponding to a 66% mortality risk reduction in multivariate analysis. The C2/C1 M-2 ratio correlated with C1 REGO+M-2+M-5 (Csum; P = 0.006). Restricted cubic spline analysis showed an increased OS benefit as the C2/C1 M-2 ratio raises and when C1 Csum ranged between 2.5 and 5.5 mg/L. Patients within the Csum range had a reduced incidence of serious adverse events and improved OS.

CONCLUSIONS

We identified PK parameters associated with a survival benefit in patients with metastatic colorectal cancer treated by REGO. OS and safety were favourable when C1 REGO+M-2+M-5 Csum ranged between 2.5 and 5.5 mg/L. These results pave the way for individual REGO dose modification strategies based on PK monitoring.

CLINICAL TRIAL REFERENCE

NCT02699073.

Broad spectrum of regorafenib activity on mutant KIT and absence of clonal selection in gastrointestinal stromal tumor (GIST): correlative analysis from the GRID trial

BACKGROUND

In the phase 3 GRID trial, regorafenib improved progression-free survival (PFS) independent of KIT mutations in exons 9 and 11. In this retrospective, exploratory analysis of the GRID trial, we investigated whether a more comprehensive KIT mutation analysis could identify mutations that impact treatment outcome with regorafenib and a regorafenib-induced mutation pattern.

METHODS

Archived tumor samples, collected at any time prior to enrollment in GRID, were analyzed by Sanger sequencing (n = 102) and next-generation sequencing (FoundationONE; n = 47). Plasma samples collected at baseline were analyzed by BEAMing (n = 163) and SafeSEQ (n = 96).

RESULTS

In archived tumor samples, 67% (68/102) had a KIT mutation; 61% (62/102) had primary KIT mutations (exons 9 and 11) and 12% (12/102) had secondary mutations (exons 13, 14, 17, and 18). At baseline, 81% of samples (78/96) had KIT mutations by SafeSEQ, including the M541L polymorphism (sole event in 6 patients). Coexisting mutations in other oncogenes were rare, as were mutations in PDGFR, KRAS, and BRAF. Regorafenib showed PFS benefit across all primary and secondary KIT mutational subgroups examined. Available patient-matched samples taken at baseline and end of treatment (n = 41; SafeSEQ), revealed heterogeneous KIT mutational changes with no specific mutation pattern emerging upon regorafenib treatment.

CONCLUSION

These data support the results of the GRID trial, and suggest that patients may benefit from regorafenib in the presence of KIT mutations and without the selection of particular mutation patterns that confer resistance. The study was not powered to address biomarker-related questions, and the results are exploratory and hypothesis-generating.

Regorafenib inhibits epithelial-mesenchymal transition and suppresses cholangiocarcinoma metastasis via YAP1-AREG axis

Cholangiocarcinoma (CCA) is a subtype of bile duct cancer usually diagnosed late with a low survival rate and no satisfactorily systemic treatment. Recently, regorafenib has been accepted as a second-line treatment for CCA patients. In this study, we investigated the potential signal transduction pathways mediated by regorafenib. We established a transcriptomic database for regorafenib-treated CCA cells using expression microarray chips. Our data indicate that regorafenib inhibits yes-associated protein 1 (YAP1) activity in various CCA cells. In addition, we demonstrated that YAP1 regulates epithelial-mesenchymal transition (EMT)-related genes, including E-cadherin and SNAI2. We further examined YAP1 activity, phosphorylation status, and expression levels of YAP1 downstream target genes in the regorafenib model. We found that regorafenib dramatically suppressed these events in CCA cells. Moreover, in vivo results revealed that regorafenib could significantly inhibit lung foci formation and tumorigenicity. Most importantly, regorafenib and amphiregulin (AREG) neutralize antibody exhibited synergistic effects against CCA cells. In a clinical setting, patients with high YAP1 and EMT expression had a worse survival rate than patients with low YAP1, and EMT expression did. In addition, we found that YAP1 upregulated the downstream target amphiregulin in CCA. Our findings suggest that AREG neutralizing antibody antibodies combined with regorafenib can reverse the CCA metastatic phenotype and EMT in vitro and in vivo. These findings provide novel therapeutic strategies to combat the metastasis of CCA.

Impact of Regorafenib on Endothelial Transdifferentiation of Glioblastoma Stem-like Cells

Glioblastomas (GBM) are aggressive brain tumours with a poor prognosis despite heavy therapy that combines surgical resection and radio-chemotherapy. The presence of a subpopulation of GBM stem cells (GSC) contributes to tumour aggressiveness, resistance and recurrence. Moreover, GBM are characterised by abnormal, abundant vascularisation. Previous studies have shown that GSC are directly involved in new vessel formation via their transdifferentiation into tumour-derived endothelial cells (TDEC) and that irradiation (IR) potentiates the pro-angiogenic capacity of TDEC via the Tie2 signalling pathway. We therefore investigated the impact of regorafenib, a multikinase inhibitor with anti-angiogenic and anti-tumourigenic activity, on GSC and TDEC obtained from irradiated GSC (TDEC IR+) or non-irradiated GSC (TDEC). Regorafenib significantly decreases GSC neurosphere formation in vitro and inhibits tumour formation in the orthotopic xenograft model. Regorafenib also inhibits transdifferentiation by decreasing CD31 expression, CD31+ cell count, pseudotube formation in vitro and the formation of functional blood vessels in vivo of TDEC and TDEC IR+. All of these results confirm that regorafenib clearly impacts GSC tumour formation and transdifferentiation and may therefore be a promising therapeutic option in combination with chemo/radiotherapy for the treatment of highly aggressive brain tumours.

Species differences in oxidative metabolism of regorafenib

Despite the prevalence of laboratory animals such as monkeys, rats, and mice in clinical drug trials, we know little regarding the oxidation of regorafenib in these test subjects. This study aimed to elucidate species differences in the kinetics of regorafenib oxidation into two metabolites: regorafenib N-oxide (M-2) and hydroxyregorafenib (M-3).M-2 formation best fitted the Hill equation and showed positive cooperativity in liver and small intestinal microsomes from all species. For all species, M-2 formation had a higher maximum velocity in microsomes from the liver than the small intestines. Maximum velocity was also higher in microsomes from humans and monkeys than those from rats and mice. M-3 formation was well-fitted to the Hill equation and showed positive cooperativity in all microsomes, except those from rat small intestines, where it exhibited biphasic kinetics. At half the maximum velocity, substrate concentration for M-2 and M-3 formation was lower in microsomes from humans than from other species. Moreover, M-2 was the major metabolite in microsomes from humans, monkeys, and mice, whereas M-2 and M-3 were the major metabolites in rat microsomes.M-2 and M-3 formation involving CYP3A4 and CYP3A5 fitted to the Hill equation. However, M-3 formation involving CYP2J2 fitted to the substrate inhibition model.Our study confirmed species differences in regorafenib oxidative metabolism.

Highly sensitive detection of anti-cancer drug based on bimetallic reduced graphene oxide nanocomposite

Herein, we describe a high-performance electrochemical sensor for the detection of regorafenib (REG) using bimetallic Pd-Ru nanoparticles anchored on pomegranate peel extract (PPE) derived reduced graphene oxide (Pd-Ru/rGO). PPE was employed to neutralize the extremely acidic graphene then cast-off along with the metal precursor for the duration of the chemical reduction to accomplish well dispersed Pd-Ru nanoparticles. Bimetallic Pd-Ru/rGO nanocomposites were synthesized using a facile chemical reduction method. Under optimal conditions, based on the differential pulse voltammetric studies it has been confirmed that the fabricated sensors has good electrocatalytic activity toward the detection of REG, spanning over the linear dynamic range of 0.5-300 nM. Moreover, the sensor exhibited a low limit of detection of 1.6 nM and a limit of quantification of 4.8 nM. The electrochemical sensor unveiled admirable selectivity and sensitivity, reproducibility, and repeatability. The fabricated sensor was suitable for real sample analysis (pharmaceutical tablet, human blood plasm, wastewater) with satisfactory recovery. The strategy presented herein can be employed in the development of electrochemical sensors for other target analytes.

Regorafenib enhances anti-PD1 immunotherapy efficacy in murine colorectal cancers and their combination prevents tumor regrowth

Background

Patients with advanced colorectal cancer (CRC) have a poor prognosis. Combinations of immunotherapies and anti-angiogenic agents are currently being evaluated in clinical trials. In this study, the multikinase inhibitor regorafenib (REG) was combined with an anti-programmed cell death protein 1 (aPD1) antibody in syngeneic murine microsatellite-stable (MSS) CT26 and hypermutated MC38 colon cancer models to gain mechanistic insights into potential drug synergism.

Methods

Growth and progression of orthotopic CT26 and subcutaneous MC38 colon cancers were studied under treatment with varying doses of REG and aPD1 alone or in combination. Sustained effects were studied after treatment discontinuation. Changes in the tumor microenvironment were assessed by dynamic contrast-enhanced MRI, and histological and molecular analyses.

Results

In both models, REG and aPD1 combination therapy significantly improved anti-tumor activity compared with single agents. However, in the CT26 model, the additive benefit of aPD1 only became apparent after treatment cessation. The combination treatment efficiently prevented tumor regrowth and completely suppressed liver metastasis, whereas the anti-tumorigenic effects of REG alone were abrogated soon after drug discontinuation. During treatment, REG significantly reduced the infiltration of immunosuppressive macrophages and regulatory T (Treg) cells into the tumor microenvironment. aPD1 significantly enhanced intratumoral IFNγ levels. The drugs synergized to induce sustained M1 polarization and durable reduction of Treg cells, which can explain the sustained tumor suppression.

Conclusions

This study highlights the synergistic immunomodulatory effects of REG and aPD1 combination therapy in mediating a sustained inhibition of colon cancer regrowth, strongly warranting clinical evaluation in CRC, including MSS tumors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02043-0.

Bioequivalence and Pharmacokinetic Evaluation of Two Oral Formulations of Regorafenib: An Open-Label, Randomised, Single-Dose, Two-Period, Two-Way Crossover Clinical Trial in Healthy Chinese Volunteers Under Fasting and Fed Conditions

Background

Regorafenib is an oral multi-kinase inhibitor approved for the treatment of solid tumours, but the pharmacokinetic profile of regorafenib in the Chinese population is unclear.

Objective

The aim of this study was to examine the pharmacokinetics, bioequivalence, and safety of two formulations of regorafenib 40 mg in healthy Chinese volunteers under fed and fasting conditions.

Methods

A single-centre, randomised, open-label, two-period, two-way crossover phase 1 trial was conducted by randomising a single oral dose of test (T) or reference (R, Stivarga^®) regorafenib (40 mg) to healthy Chinese volunteers under both fasting and fed conditions (high-fat and high-calorie diet). Pharmacokinetic parameters were calculated using non-compartmental methods. Adverse events were recorded to assess drug safety.

Results

Sixty-six participants were enrolled for both fasting and fed treatments. The 90% CIs geometric least-square means of ratio_T/R for regorafenib were completely contained within the equivalence margin of 80–125% under both fasting and fed conditions. Both formulations displayed similar and generally good safety profiles.

Conclusion

Single oral dose of the T (40 mg) and R (40 mg) regorafenib was bioequivalent under fasting and fed conditions and had similar favourable safety profiles among healthy Chinese volunteers.

Targeting MSS colorectal cancer with immunotherapy: are we turning the corner?

INTRODUCTION

Immunotherapy with checkpoint inhibition has shown potent antitumor activity in patients with microsatellite instability (MSI) metastatic cancer. Microsatellite stable (MSS) colorectal cancer has long been considered resistant to immunotherapy.

AREAS COVERED

In this review, we provide an overview of current progress on strategies to overcome the resistance to immunotherapy in MSS colorectal cancer.

EXPERT OPINION

Emerging evidence suggest that combination of immune modulators such as regorafenib may improve the responsiveness of MSS colorectal cancer to checkpoint blockade. In addition, signs of clinical activity have also been observed in other combination strategies, such as the combination of checkpoint blockade with Stat3 inhibitor, or bispecific T-cell engagers. Nevertheless, predictive biomarkers that can identify patients who may benefit from immunotherapy are key for its implementation in clinical setting. Metastatic disease sites may predict for the response or resistance to checkpoint blockade, with liver metastases emerging as a strong predictive biomarker of lack of benefit from PD-1 targeting, even with combination therapies. Additional efforts are required to study the mechanism of resistance and to develop novel therapeutic strategies to overcome immune resistance.

ABBREVIATIONS

CEA: carcinoembryonic antigen; CR: complete response; CTLA-4: cytotoxic T-lymphocyte-associated protein 4; DCR: disease control rate; MSI-H: microsatellite instability-high; MSS: Microsatellite stable (MSS); OS: overall survival; PD-1: programmed cell death protein 1; PD-L1: programmed death-ligand receptor 1; PR: partial response; PFS: progression-free survival; SD: stable disease; TMB: tumor mutation burden; VEGFR: vascular endothelial growth factor receptor.

Regorafenib Combined with Other Systemic Therapies: Exploring Promising Therapeutic Combinations in HCC

Regorafenib was the first drug to demonstrate a survival benefit as a second-line agent after sorafenib failure in patients with unresectable hepatocellular carcinoma (HCC). Recent studies have shown that its mechanism of action is not only limited to its very broad spectrum of inhibition of angiogenesis, tumor proliferation, spread, and metastasis, but also to its immunomodulatory properties that have favorable effects on the very intricate role that the tumor microenvironment plays in carcinogenesis and tumor growth. In this review, we discuss rationale and evidence supporting regorafenib efficacy in HCC and that led to its approval as a second-line treatment, after sorafenib failure. We also discuss the evidence from clinical practice studies that confirm the results previously achieved in clinical trials. Finally, we analyze the potential role of regorafenib in emerging combined treatment approach with immunotherapy strategies using immune checkpoint blockade and its potential extension to patient categories not included in the registrative study.

Real-world safety and effectiveness of regorafenib in metastatic colorectal cancer: the French CORRELATE cohort

Aim: We report real-world evidence with regorafenib in previously treated metastatic colorectal cancer from the French cohort of the international, prospective, observational CORRELATE study. Patients & methods: Patients receiving regorafenib according to French health authority approval were included. The primary end point was treatment-emergent adverse events. Overall survival and progression-free survival were secondary end points. Results: Two hundred and forty-two patients (61% male, median age: 66 years) were enrolled. The most common grade ≥3 drug-related treatment-emergent adverse events were hand-foot skin reaction (10.3%), asthenia/fatigue (9.9/1.2%) and hypertension (6.2%). Median overall survival and progression-free survival were 6.8 (95% CI: 6.3-7.6) and 2.8 months (95% CI: 2.6-3.0), respectively. Conclusion: The real-world safety and effectiveness data of regorafenib in metastatic colorectal cancer in France align with findings from Phase III clinical trials and the global CORRELATE population.

Association of albumin-bilirubin score in patients with colorectal cancer receiving later-line chemotherapy with regorafenib

BACKGROUND

Regorafenib is recognized as a later-line standard treatment in patients with metastatic colorectal cancer (mCRC). In this study, we examined the association of the albumin-bilirubin (ALBI) score in patients with mCRC receiving later-line chemotherapy with regorafenib.

PATIENTS AND METHODS

We retrospectively analyzed data from patients with mCRC treated with regorafenib in a later line between January 2013 and December 2019. Patients were divided into a Normal-ALBI group (ALBI grade 1) and a High-ALBI group (ALBI grades 2 and 3). Primary endpoint was median overall survival (OS) and secondary endpoints were median time to treatment failure (TTF) and incidence of adverse events (AEs).

RESULTS

Data from 60 patients were analyzed (Normal-ALBI group: 32 patients and High-ALBI group: 28 patients). Median OS [10.23 vs. 3.70 months, hazard ratio (HR): 1.79, 95% confidence interval (CI) 1.02-3.13, p = 0.041] and median TTF (2.27 vs. 1.78 months, HR: 1.78, 95%CI 1.02-3.09, p = 0.042) were significantly longer in the Normal-ALBI group than High-ALBI group. On Cox proportional hazard analysis, ALBI score was significantly correlated with OS. The incidence of liver dysfunction (grade ≥ 2) was significantly higher in the High-ALBI than the Normal-ALBI group (42.9% vs. 15.6%, p = 0.041), whereas other AEs were comparable between the two groups.

CONCLUSION

ALBI was strongly associated with the prognosis of patients with mCRC treated with regorafenib and with the occurrence of liver-related adverse events. These findings may imply that patients with a high ALBI score should not be treated with regorafenib.

Regorafenib enhances antitumor immunity via inhibition of p38 kinase/Creb1/Klf4 axis in tumor-associated macrophages

BACKGROUND

Regorafenib and other multikinase inhibitors may enhance antitumor efficacy of anti-program cell death-1 (anti-PD1) therapy in hepatocellular carcinoma (HCC). Its immunomodulatory effects, besides anti-angiogenesis, were not clearly defined.

METHODS

In vivo antitumor efficacy was tested in multiple syngeneic liver cancer models. Murine bone marrow-derived macrophages (BMDMs) were tested in vitro for modulation of polarization by regorafenib and activation of cocultured T cells. Markers of M1/M2 polarization were measured by quantitative reverse transcription PCR (RT-PCR), arginase activity, flow cytometry, and ELISA. Knockdown of p38 kinase and downstream Creb1/Klf4 signaling on macrophage polarization were confirmed by using knockdown of the upstream MAPK14 kinase, chemical p38 kinase inhibitor, and chromatin immunoprecipitation.

RESULTS

Regorafenib (5 mg/kg/day, corresponding to about half of human clinical dosage) inhibited tumor growth and angiogenesis in vivo similarly to DC-101 (anti-VEGFR2 antibody) but produced higher T cell activation and M1 macrophage polarization, increased the ratio of M1/M2 polarized BMDMs and proliferation/activation of cocultured T cells in vitro, indicating angiogenesis-independent immunomodulatory effects. Suppression of p38 kinase phosphorylation and downstream Creb1/Klf4 activity in BMDMs by regorafenib reversed M2 polarization. Regorafenib enhanced antitumor efficacy of adoptively transferred antigen-specific T cells. Synergistic antitumor efficacy between regorafenib and anti-PD1 was associated with multiple immune-related pathways in the tumor microenvironment.

CONCLUSION

Regorafenib may enhance antitumor immunity through modulation of macrophage polarization, independent of its anti-angiogenic effects. Optimization of regorafenib dosage for rational design of combination therapy regimen may improve the therapeutic index in the clinic.

Associations among plasma concentrations of regorafenib and its metabolites, adverse events, and ABCG2 polymorphisms in patients with metastatic colorectal cancers

PURPOSE

The association between the pharmacokinetics and pharmacodynamics of regorafenib, a multiple tyrosine kinase inhibitor, remains unclear. This study assessed the trough plasma concentrations (C_trough) of regorafenib and its N-oxide (M2) and N-oxide/desmethyl (M5) metabolites, and evaluated the associations among these levels, adverse events, and pharmacokinetic-related genetic polymorphisms in patients with metastatic colorectal cancer.

METHODS

The C_trough levels of regorafenib and its metabolites were assessed in a single-center, prospective, observational study, 7 days after the initial treatment. The correlation between those values and adverse events was then examined. In addition, the genetic polymorphisms of ABCG2, SLCO1B1, and UGT1A9 were determined and evaluated for associations with the levels of regorafenib, M2, and M5.

RESULTS

We analyzed 43 patients who received regorafenib 40-120 mg/day; among them, 35 patients started at 120 mg/day. With regard to bilirubin increase, the C_trough values of regorafenib were significantly higher in the group with grade ≥ 2 than in groups with grades 0 and 1 (p = 0.010). The M5 C_trough levels were significantly associated with the severity of hypertension or rash (p < 0.05). In a multivariate analysis, the M5 C_trough values and age were significant predictors of severe rash. Lastly, significant differences were noted in the M5 concentration-to-dose ratio values between the patients with ABCG2 421A/A and ABCG2 421C/A or C/C polymorphisms (p = 0.035).

CONCLUSION

This study showed that the C_trough of regorafenib was associated with bilirubin increase, and also clarified for the first time that the C_trough of M5 was significantly correlated with hypertension and severe rash.

Quality-adjusted survival in patients with metastatic colorectal cancer treated with fruquintinib in the FRESCO trial

Aim: To assess whether the survival benefit of fruquintinib is quality-adjusted. Materials & methods: Data of 416 metastatic colorectal cancer patients from the Phase III FRESCO trial were used. The Quality-adjusted Time Without Symptoms or Toxicity (Q-TWiST) analysis assessed the quality-adjusted survival benefit of fruquintinib versus placebo, accounting for freedom from symptomatic disease and from severe side effects of treatment. Results: Fruquintinib significantly improved patients' Q-TWiST (difference: 2.23 [1.41, 3.04] months) versus placebo. The Q-TWiST gain was 28.3% in the base case and ranged from 16.7 to 39.9% in the threshold analysis, favoring fruquintinib. The Q-TWiST benefit was observed in fruquintinib-treated patients regardless of prior targeted therapy. Conclusion: Fruquintinib provides a clinically meaningful quality-adjusted survival benefit versus placebo as a third-line treatment for metastatic colorectal cancer patients.

Therapeutic Potential of Regorafenib-A Multikinase Inhibitor in Pulmonary Hypertension

Pulmonary hypertension (PH) is characterized by a progressive elevation of mean arterial pressure followed by right ventricular failure and death. Previous studies have indicated that numerous inhibitors of receptor tyrosine kinase signaling could be either beneficial or detrimental for the treatment of PH. Here we investigated the therapeutic potential of the multi-kinase inhibitor regorafenib (BAY 73-4506) for the treatment of PH. A peptide-based kinase activity assay was performed using the PamStation^®12 platform. The 5-bromo-2′-deoxyuridine proliferation and transwell migration assays were utilized in pulmonary arterial smooth muscle cells (PASMCs). Regorafenib was administered to monocrotaline- and hypoxia-induced PH in rats and mice, respectively. Functional parameters were analyzed by hemodynamic and echocardiographic measurements. The kinase activity assay revealed upregulation of twenty-nine kinases in PASMCs from patients with idiopathic PAH (IPAH), of which fifteen were established as potential targets of regorafenib. Regorafenib showed strong anti-proliferative and anti-migratory effects in IPAH-PASMCs compared to the control PASMCs. Both experimental models indicated improved cardiac function and reduced pulmonary vascular remodeling upon regorafenib treatment. In lungs from monocrotaline (MCT) rats, regorafenib reduced the phosphorylation of c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2. Overall, our data indicated that regorafenib plays a beneficial role in experimental PH.

Experience with regorafenib in the treatment of hepatocellular carcinoma

Regorafenib is a diphenylurea oral multikinase inhibitor, structurally comparable to sorafenib, which targets a variety of kinases implicated in angiogenic and tumor growth-promoting pathways. Regorafenib was the first agent to positively show significant survival advantage as a second-line therapy in patients with unresectable hepatocellular carcinoma (HCC) who had previously failed first-line treatment with sorafenib. Recent evidence has shown that its antitumor efficacy is due to a comprehensive spectrum of tumor neo-angiogenesis and proliferation inhibition and immunomodulatory effects on the tumor microenvironment, which plays a crucial role in tumor development. This review addresses the rationale and supporting evidence for regorafenib's efficacy in HCC that led to regorafenib's approval as a second-line therapy. In addition, we review proof from clinical practice studies that validate the RESORCE trial results. We discuss regorafenib's potential role in the newly emerging therapeutic strategy based on combination with immune checkpoint blockade and its possible extensibility to patient categories not enrolled in the registrative study.

Regorafenib combined with PD1 blockade increases CD8 T-cell infiltration by inducing CXCL10 expression in hepatocellular carcinoma

BACKGROUND AND PURPOSE

Combining inhibitors of vascular endothelial growth factor and the programmed cell death protein 1 (PD1) pathway has shown efficacy in multiple cancers, but the disease-specific and agent-specific mechanisms of benefit remain unclear. We examined the efficacy and defined the mechanisms of benefit when combining regorafenib (a multikinase antivascular endothelial growth factor receptor inhibitor) with PD1 blockade in murine hepatocellular carcinoma (HCC) models.

BASIC PROCEDURES

We used orthotopic models of HCC in mice with liver damage to test the effects of regorafenib-dosed orally at 5, 10 or 20 mg/kg daily-combined with anti-PD1 antibodies (10 mg/kg intraperitoneally thrice weekly). We evaluated the effects of therapy on tumor vasculature and immune microenvironment using immunofluorescence, flow cytometry, RNA-sequencing, ELISA and pharmacokinetic/pharmacodynamic studies in mice and in tissue and blood samples from patients with cancer.

MAIN FINDINGS

Regorafenib/anti-PD1 combination therapy increased survival compared with regofarenib or anti-PD1 alone in a regorafenib dose-dependent manner. Combination therapy increased regorafenib uptake into the tumor tissues by normalizing the HCC vasculature and increasing CD8 T-cell infiltration and activation at an intermediate regorafenib dose. The efficacy of regorafenib/anti-PD1 therapy was compromised in mice lacking functional T cells (Rag1-deficient mice). Regorafenib treatment increased the transcription and protein expression of CXCL10-a ligand for CXCR3 expressed on tumor-infiltrating lymphocytes-in murine HCC and in blood of patients with HCC. Using Cxcr3-deficient mice, we demonstrate that CXCR3 mediated the increased intratumoral CD8 T-cell infiltration and the added survival benefit when regorafenib was combined with anti-PD1 therapy.

PRINCIPAL CONCLUSIONS

Judicious regorafenib/anti-PD1 combination therapy can inhibit tumor growth and increase survival by normalizing tumor vasculature and increasing intratumoral CXCR3+CD8 T-cell infiltration through elevated CXCL10 expression in HCC cells.

Clinical Pharmacokinetics and Pharmacodynamics of Transarterial Chemoembolization and Targeted Therapies in Hepatocellular Carcinoma

The management of hepatocellular carcinoma (HCC) is based on a multidisciplinary decision tree. Treatment includes loco-regional therapy, mainly transarterial chemoembolization, for intermediate-stage HCC and systemic therapy with oral tyrosine kinase inhibitors (TKIs) for advanced HCC. Transarterial chemoembolization involves hepatic intra-arterial infusion with either conventional procedure or drug-eluting-beads. The aim of the loco-regional procedure is to deliver treatment as close as possible to the tumor both to embolize the tumor area and to enhance efficacy and minimize systemic toxicity of the anticancer drug. Pharmacokinetic studies applied to transarterial chemoembolization are rare and pharmacodynamic studies even rarer. However, all available studies lead to the same conclusions: use of the transarterial route lowers systemic exposure to the cytotoxic drug and leads to much higher tumor drug concentrations than does a similar dose via the intravenous route. However, reproducibility of the procedure remains a major problem, and no consensus exists regarding the choice of anticancer drug and its dosage. Systemic therapy with TKIs is based on sorafenib and lenvatinib as first-line treatment and regorafenib and cabozantinib as second-line treatment. Clinical use of TKIs is challenging because of their complex pharmacokinetics, with high liver metabolism yielding both active metabolites and their common toxicities. Changes in liver function over time with the progression of HCC adds further complexity to the use of TKIs. The challenges posed by TKIs and the HCC disease process means monitoring of TKIs is required to improve clinical management. To date, only partial data supporting sorafenib monitoring is available. Results from further pharmacokinetic/pharmacodynamic studies of these four TKIs are eagerly awaited and are expected to permit such monitoring and the development of consensus guidelines.

Regorafenib and Nivolumab or Pembrolizumab Combination and Circulating Tumor DNA Response Assessment in Refractory Microsatellite Stable Colorectal Cancer

BACKGROUND

Metastatic colorectal cancers (MCRCs) with microsatellite stability (MSS) are resistant to immunotherapy with programmed cell death protein 1 (PD-1) and programmed death-ligand 1 inhibitors. However, the addition of regorafenib to nivolumab was recently associated with a high response rate and a protracted progression-free survival in a small cohort of MSS Japanese patients with metastatic colorectal cancer.

MATERIALS AND METHODS

We evaluated the outcome of patients with MSS metastatic colorectal cancer who were treated on a compassionate basis with PD-1 inhibitors in combination with regorafenib in a single U.S. center.

RESULTS

A total of 18 patients were treated with a combination of regorafenib and PD-1 inhibitors. No treatment-related grade 3 or above toxicities were noted. Thirteen patients (69%) had progressive disease, and five patients (31%) experienced stable disease as best response. Four out of five stable diseases occurred in patients without liver metastases, whereas only 1 of 14 patients with history of liver metastases had a short disease stabilization. A rise in circulating tumor DNA (ctDNA) at the 4-week time pointuniversally predicted tumor progression at 2 months, whereas a decline was associated with radiographic disease stabilization.

CONCLUSIONS

Regorafenib and nivolumab combination was associated with modest clinical activity in patients with MSS chemotherapy-resistant metastatic colorectal cancer. Selection for patients without history of liver metastases may identify a cohort of patients with MSS colorectal cancer with a higher likelihood of benefit from this combination. ctDNA may represent a powerful tool for predicting early therapeutic efficacy of immunotherapy in the MSS colorectal cancer population.

IMPLICATIONS FOR PRACTICE

This study showed that the combination of regorafenib and nivolumab was associated with a modest clinical activity in patients with advanced microsatellite stability (MSS) metastatic colorectal cancer. This combination should be avoided in clinical practice, especially in patients with MSS colorectal cancer with liver metastases. Further investigation of regorafenib plus PD-1 inhibitors should be considered in MSS colorectal cancer without liver metastases.

Population pharmacokinetics of regorafenib in solid tumours: Exposure in clinical practice considering enterohepatic circulation and food intake

Aim

Regorafenib is an oral multikinase inhibitor with clinical efficacy in a range of advanced solid tumours. A population pharmacokinetic (PK) model was developed to evaluate the variability of the PK of regorafenib and its pharmacologically active metabolites M‐2 and M‐5 in solid tumours.

Methods

The model was initially developed using densely sampled phase 1 data and information on food intake to incorporate enterohepatic circulation (EHC) that was identified to considerably contribute to the PK of regorafenib. This was then applied to sparsely sampled data from four phase 3 studies in patients with advanced solid tumours. The need for exact food intake data to estimate individual drug exposure was evaluated.

Results

By incorporating EHC, the model adequately described the PK profiles of regorafenib, M‐2 and M‐5 after single and multiple doses in patients from phase 1 studies. Individual exposure in phase 3 studies was adequately described based on assumptions on the time and frequency of food intake, although exact food intake data are recommended to improve the estimation. Covariate analysis identified sex and body mass index (BMI) as impacting exposure to regorafenib, and sex as strongly impacting exposure to M‐2 and M‐5 (also influenced by the BMI effect on parent regorafenib in the joint model developed); however, these factors accounted for a small portion of the overall variability in exposure.

Conclusions

The adequate description of regorafenib PK after multiple dosing requires the incorporation of EHC. Neither single nor combined covariates predicted exposures that would warrant a priori regorafenib dose adjustment.

Cerebrospinal fluid penetration of targeted therapeutics in pediatric brain tumor patients

Treatment with small-molecule inhibitors, guided by precision medicine has improved patient outcomes in multiple cancer types. However, these compounds are often not effective against central nervous system (CNS) tumors. The failure of precision medicine approaches for CNS tumors is frequently attributed to the inability of these compounds to cross the blood-brain barrier (BBB), which impedes intratumoral target engagement. This is complicated by the fact that information on CNS penetration in CNS-tumor patients is still very limited. Herein, we evaluated cerebrospinal fluid (CSF) drug penetration, a well-established surrogate for CNS-penetration, in pediatric brain tumor patients. We analyzed 7 different oral anti-cancer drugs and their metabolites by high performance liquid chromatography mass spectrometry (HPLC-MS) in 42 CSF samples obtained via Ommaya reservoirs of 9 different patients. Moreover, we related the resulting data to commonly applied predictors of BBB-penetration including ABCB1 substrate-character, physicochemical properties and in silico algorithms. First, the measured CSF drug concentrations depicted good intra- and interpatient precision. Interestingly, ribociclib, vorinostat and imatinib showed high (> 10 nM), regorafenib and dasatinib moderate (1-10 nM) penetrance. In contrast, panobinostat und nintedanib were not detected. In addition, we identified active metabolites of imatinib and ribociclib. Comparison to well-established BBB-penetrance predictors confirmed low molecular weight, high proportion of free-drug and low ABCB1-mediated efflux as central factors. However, evaluation of diverse in silico algorithms showed poor correlation within our dataset. In summary, our study proves the feasibility of measuring CSF concentration via Ommaya reservoirs thus setting the ground for utilization of this method in future clinical trials. Moreover, we demonstrate CNS presence of certain small-molecule inhibitors and even active metabolites in CSF of CNS-tumor patients and provide a potential guidance for physicochemical and biological factors favoring CNS-penetration.

Imaging and clinical correlates with regorafenib in metastatic colorectal cancer

In colorectal cancer (CRC), imaging is important in determining tumor stage, selecting treatment strategies, and in assessing response to therapy. However, some challenges remain with established imaging techniques, such as computed tomography, and with some commonly used response criteria, such as Response Evaluation Criteria in Solid Tumors, which measures change in size of several target lesions instead of change in tumor morphology or metabolic function. In addition, these assessments are not typically conducted until after 8 weeks of treatment, meaning that potential non-responders are often not identified in a timely manner. Regorafenib, an oral tyrosine kinase inhibitor indicated for the treatment of metastatic CRC, blocks the activity of several protein kinases involved in angiogenesis, oncogenesis, metastasis, and tumor immunity. Timely differentiation of regorafenib responders from non-responders using appropriate imaging techniques that recognize not only changes in tumor size but also changes in tumor density or vasculature, may reduce unnecessary drug-related toxicity in patients who are unlikely to respond to treatment. This review discusses the latest developments in computed tomography, magnetic resonance imaging, and positron emission tomography tumor imaging modalities, and how these aid in identifying patients with metastatic CRC who are responders or non-responders to regorafenib treatment.

Higher Systemic Exposure to Unbound Active Metabolites of Regorafenib Is Associated With Short Progression-Free Survival in Colorectal Cancer Patients

Regorafenib treatment improves survival of patients with metastatic colorectal cancer, but it is also characterized by detrimental side effects that may require modified dosing or interval schedules. Regorafenib is metabolized by cytochrome P450 3A4 in the liver to its active metabolites, M-2 and M-5. We examined area under the unbound plasma concentration-time curve (AUCu) to these compounds to establish pharmacokinetic bases for individualized dosing strategies. The plasma protein binding of M-2 and M-5 was approximately 10-fold lower than that of regorafenib, whereas AUCu values for active metabolites on both days 1 and 15 were significantly higher than that of regorafenib. Patients with higher AUCu values of M-2 or M-5 on day 1 showed significantly shorter progression-free survival than others, likely due, at least in part, to treatment discontinuation as a result of adverse events, especially occurred during first cycle.

Inactivation of Transcriptional Repressor Capicua Confers Sorafenib Resistance in Human Hepatocellular Carcinoma

BACKGROUND & AIMS

Sorafenib is a multireceptor tyrosine kinase inhibitor that can prolong overall survival in patients with advanced hepatocellular carcinoma (HCC). Although most HCC patients who receive sorafenib ultimately show disease progression, it still is unclear whether and how HCC cells acquire chemoresistance during sorafenib treatment in human beings.

METHODS

We analyzed surgically resected HCC tissues from a patient who received sorafenib for prevention of HCC recurrence after surgery (Adjuvant Sorafenib for Hepatocellular Carcinoma after Resection or Ablation trial) and established patient-derived HCC cells. Whole-exome sequence analysis was performed to detect mutations in sorafenib-resistant clones. We examined 30 advanced HCC cases immunohistochemically and 140 HCC cases enrolled in the Adjuvant Sorafenib for Hepatocellular Carcinoma after Resection or Ablation trial using microarray analysis to evaluate the association of Capicua Transcriptional Repressor (CIC) status with sorafenib treatment response.

RESULTS

We found a CIC mutation in recurrent HCC specimens after sorafenib. CIC encodes Capicua, a general sensor of receptor tyrosine kinase signaling. HCC cells established from the recurrent tumor specimen showed chemoresistance to sorafenib in vitro and in vivo. Established sorafenib-resistant Huh1 and Huh7 cell lines showed reduced expression of Capicua without mutations. Immunohistochemical analysis showed that HCC patients with low Capicua expression showed poor overall survival. Microarray analysis showed that the CIC gene signature could predict the preventive effect of adjuvant sorafenib treatment on HCC recurrence. Intriguingly, although CIC knockdown induced sorafenib resistance in HCC cell lines, regorafenib suppressed growth of sorafenib-resistant, Capicua-inactivated HCC cells and inhibited extracellular signal-regulated kinase phosphorylation.

CONCLUSIONS

Evaluation of Capicua status may be pivotal to predict response to sorafenib, and regorafenib treatment could be effective to treat HCC with functional Capicua impairment.

Regorafenib-loaded poly (lactide-co-glycolide) microspheres designed to improve transarterial chemoembolization therapy for hepatocellular carcinoma

Transarterial chemoembolization (TACE) has been widely introduced to treat hepatocellular carcinoma (HCC) especially for unresectable patients for decades. However, TACE evokes an angiogenic response due to the secretion of vascular endothelial growth factor (VEGF), resulting in the formation of new blood vessels and eventually tumor recurrence. Thus, we aimed to develop regorafenib (REGO)-loaded poly (lactide-co-glycolide) (PLGA) microspheres that enabled localized and sustained drug delivery to limit proangiogenic responses following TACE in HCC treatment. REGO-loaded PLGA microspheres were prepared using the emulsion-solvent evaporation/extraction method, in which DMF was selected as an organic phase co-solvent. Accordingly, we optimized the proportion of DMF, which the optimal ratio to DCM was 1:9 (v/v). After preparation, the microspheres provided high drug loading capacity of 28.6%, high loading efficiency of 91.5%, and the average particle size of 149 µm for TACE. IR spectra and XRD were applied to confirming sufficient REGO entrapment. The in vitro release profiles demonstrated sustained drug release of microspheres for more than 30 d To confirm the role of REGO-loaded microspheres in TACE, the cell cytotoxic activity on HepG2 cells and anti-angiogenic effects in HUVECs Tube-formation assay were studied in combination with miriplatin. Moreover, the microspheres indicated the potential of antagonizing miriplatin resistance of HepG2 cells in vitro. Pharmacokinetics preliminary studies exhibited that REGO could be sustainably released from microspheres for more than 30 d after TACE in vivo. In vivo anti-tumor efficacy was further determined in HepG2 xenograft tumor mouse model, demonstrating that REGO microspheres could improve the antitumor efficacy of miriplatin remarkably compared with miriplatin monotherapy. In conclusion, the obtained REGO microspheres demonstrated promising therapeutic effects against HCC when combined with TACE.

Regorafenib CSF Penetration, Efficacy, and MRI Patterns in Recurrent Malignant Glioma Patients

(1) Background: The phase 2 Regorafenib in Relapsed Glioblastoma (REGOMA) trial indicated a survival benefit for patients with first recurrence of a glioblastoma when treated with the multikinase inhibitor regorafenib (REG) instead of lomustine. The aim of this retrospective study was to investigate REG penetration to cerebrospinal fluid (CSF), treatment efficacy, and effects on magnetic resonance imaging (MRI) in patients with recurrent high-grade gliomas. (2) Methods: Patients were characterized by histology, adverse events, steroid treatment, overall survival (OS), and MRI growth pattern. REG and its two active metabolites were quantified by liquid chromatography/tandem mass spectrometry in patients’ serum and CSF. (3) Results: 21 patients mainly with IDH-wildtype glioblastomas who had been treated with REG were retrospectively identified. Thirteen CFS samples collected from 3 patients of the cohort were available for pharmacokinetic testing. CSF levels of REG and its metabolites were significantly lower than in serum. Follow-up MRI was available in 19 patients and showed progressive disease (PD) in all but 2 patients. Two distinct MRI patterns were identified: 7 patients showed classic PD with progression of contrast enhancing lesions, whereas 11 patients showed a T2-dominant MRI pattern characterized by a marked reduction of contrast enhancement. Median OS was significantly better in patients with a T2-dominant growth pattern (10 vs. 27 weeks respectively, p = 0.003). Diffusion restrictions were observed in 13 patients. (4) Conclusion: REG and its metabolites were detectable in CSF. A distinct MRI pattern that might be associated with an improved OS was observed in half of the patient cohort. Treatment response in the total cohort was poor.

The landscape of tyrosine kinase inhibitors in sarcomas: looking beyond pazopanib

Introduction: Tyrosine kinases are key mediators of intracellular signaling cascades and aberrations in these proteins have been implicated in driving oncogenesis through the dysregulation of fundamental cellular processes including proliferation, migration, and apoptosis. As such, targeting these proteins with small molecule tyrosine kinase inhibitors (TKI) has led to significant advances in the treatment of a number of cancer types.Areas covered: Soft tissue sarcomas (STS) are a heterogeneous and challenging group of rare cancers to treat, but the approval of the TKI pazopanib for the treatment of advanced STS demonstrates that this class of drugs may have broad utility against a range of different sarcoma histological subtypes. Since the approval of pazopanib, a number of other TKIs have entered clinical trials to evaluate whether their activity in STS matches the promising results seen in other solid tumors. In this article, we review the emerging role of TKIs in the evolving landscape of sarcoma treatment.Expert opinion: As our biological understanding of response and resistance of STS to TKIs advances, we anticipate that patient management will move away from a 'one size fits all' paradigm toward personalized, multi-line, and patient-specific treatment regimens where patients are treated according to the underlying biology and genetics of their specific disease.